It should be. In the GMCs, they used the Dana axle instead of the Eatons that the Chevrolets used. For a positive ID, take a look on the front snout of the center cection, just above the pinion. It should have a "44" cast into it. The "44" may also be present on the rear face of the housing, to the left of the cover. Spicer/Dana casts the differential model number on the ceter castings. It may also be stamped on the cover, though that isn't always the case.
